If your Gun has a Cocking Pin with different size diameters above and below the locking groove, you'll need to upgrade to the Cocking Pin 131210-000 or 131789-000.

Will NOT work with 131951-000 Cocking Pin.

This vertical adapter mounts in to the body of the gun where the hose or foregrip currently is in place. It lets you attach to the bottom of it any standard ASA item like regulators and expansion chambers.